The present invention relates to a support tube for cross-wound coils and cross-windings for bleaching and dyeing shrinking yarns, consisting of a strip, closed in itself, of a porous, elastic nonwoven fabric of synthetic fibers and/or endless fibers which are connected to each other.
A support tube of the type mentioned above is known from DE-OS 22 47 751. The support tube consists of a thickwalled hollow cylinder or hollow cone of an elastic nonwoven fabric, the wall thickness of which is made so that the yarn winding taken-up is securely held from the start without adverse effect from the diameter reduction resulting from the shrinkage. Because of the large fiber volume, the cost of the materials for such a support tube is relatively high. In addition, the compression of the wall thickness of the support tube due to the shrinkage of the yarn thereon can result in a reduction of the pore volume and, in particular, of the pore radii, of the nonwoven fabric, which has an adverse effect on the permeability of the fabric and, therefore, on the uniformity with which the individual layers of the yarn winding are acted on by the subsequent treatment (i.e., dyeing or bleaching) liquor.